关于创建子窗口,该怎么处理

关于创建子窗口
LRESULT   CALLBACK   WndProc(HWND   hWnd,   UINT   message,   WPARAM   wParam,   LPARAM   lParam) //父窗口过程
{
int   wmId,   wmEvent;
PAINTSTRUCT   ps;
HDC   hdc;
int   cxClient,cyClient;

switch   (message)
{
case   WM_CREATE: //把窗口分成左右两个子窗口   LHwnd，RHwnd   存在全局变量中
MyRegisterChildClass(hInst);
LHwnd   =   CreateWindow(TEXT( "Child "),NULL,WS_CHILDWINDOW|WS_VISIBLE,0,0,0,0,hWnd,NULL,hInst,NULL);
RHwnd   =   CreateWindow(TEXT( "Child "),NULL,WS_CHILDWINDOW|WS_VISIBLE,0,0,0,0,hWnd,NULL,hInst,NULL);
break;
case   WM_SIZE:
cxClient   =   LOWORD(lParam);
cyClient   =   HIWORD(lParam);
MoveWindow(LHwnd,0,0,cxClient/2,cyClient,true);
MoveWindow(RHwnd,cxClient/2,0,cxClient/2,cyClient,true);
break;
case   WM_COMMAND:
wmId         =   LOWORD(wParam);
wmEvent   =   HIWORD(wParam);
//   分析菜单选择:
switch   (wmId)
{
case   IDM_ABOUT:
DialogBox(hInst,   MAKEINTRESOURCE(IDD_ABOUTBOX),   hWnd,   About);
break;
case   IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return   DefWindowProc(hWnd,   message,   wParam,   lParam);
}
break;
case   WM_PAINT:
hdc   =   BeginPaint(hWnd,   &ps);
//   TODO:   在此添加任意绘图代码...
EndPaint(hWnd,   &ps);
break;
case   WM_DESTROY:
PostQuitMessage(0);
break;
default:
return   DefWindowProc(hWnd,   message,   wParam,   lParam);
}
return   0;
}


LRESULT   CALLBACK   ChildWndProc(HWND   hWnd,   UINT   message,   WPARAM   wParam,   LPARAM   lParam) //子窗口消息处理过程
{
PAINTSTRUCT   ps;
HDC   hdc;
switch(message)
{
case   WM_CREATE:
MessageBox(hWnd,TEXT( "ChildWindow   Create   Successfully "),TEXT( "CHILD   ONE "),MB_OKCANCEL); //提示子窗口建立成功
break;

case   WM_PAINT:
hdc   =   BeginPaint(hWnd,   &ps);
//   TODO:   在此添加任意绘图代码...
EndPaint(hWnd,   &ps);
break;
case   WM_DESTROY:
PostQuitMessage(0);
break;

default:
return   DefWindowProc(hWnd,message,wParam,lParam);

}
return   0;
}

ATOM   MyRegisterChildClass(HINSTANCE   hInstance) //注册子窗口类
{
WNDCLASSEX   ChildClass;
ChildClass.cbSize   =   sizeof(WNDCLASSEX);
ChildClass.style   =   CS_HREDRAW|CS_VREDRAW;
ChildClass.cbClsExtra   =   0;
ChildClass.cbWndExtra   =   0;
ChildClass.hCursor   =   NULL;
ChildClass.hIcon   =   NULL;
ChildClass.hIconSm   =   NULL;
ChildClass.lpszMenuName   =   NULL;
ChildClass.lpfnWndProc   =   ChildWndProc;
ChildClass.hbrBackground   =   (HBRUSH)GetStockObject(WHITE_BRUSH);
ChildClass.lpszClassName   =   TEXT( "Child ");
return   RegisterClassEx(&ChildClass);
}


到主窗口处理WM_CREATE的时候   LHwnd和RHwnd在CreateWindow以后都是0X0000000
子窗口就没有创建   怎么回事啊？

------解决方案--------------------
接分